﻿462 
  

  

  L. 
  D. 
  CLEARE, 
  JR. 
  

  

  Further 
  proof 
  of 
  this 
  greater 
  infestation 
  in 
  the 
  field 
  in 
  which 
  the 
  old 
  bank 
  is 
  left 
  

   is 
  given 
  by 
  the 
  collections 
  of 
  the 
  gang* 
  from 
  these 
  fields. 
  These 
  figures 
  are 
  given 
  

   below. 
  

  

  Larvae 
  Clusters 
  

  

  Field. 
  collected. 
  collected. 
  

  

  No. 
  1 
  6,630 
  462 
  

  

  No. 
  3 
  19,910 
  1,732 
  

  

  It 
  can 
  be 
  readily 
  seen 
  from 
  the 
  above 
  that 
  these 
  old 
  banks 
  actually 
  foster 
  moth- 
  

   borers, 
  causing 
  a 
  much 
  higher 
  infestation 
  in 
  the 
  plants 
  than 
  would 
  otherwise 
  occur. 
  

   The 
  obvious 
  thing 
  to 
  do 
  is 
  to 
  fork 
  both 
  banks 
  as 
  soon 
  as 
  the 
  tops 
  are 
  planted. 
  

  

  Planting 
  Borer-free 
  Tops. 
  

  

  Provided 
  that 
  both 
  banks 
  are 
  forked 
  and 
  the 
  trash 
  is 
  buried, 
  the 
  next 
  most 
  

   important 
  source 
  of 
  early 
  infestation 
  in 
  plant 
  fields 
  is 
  the 
  tops 
  themselves. 
  The 
  

   selection 
  of 
  borer-free 
  tops 
  for 
  planting 
  has 
  been 
  recommended 
  by 
  Quelch 
  and 
  Moore, 
  

   but 
  it 
  has 
  been 
  invariably 
  objected 
  to 
  from 
  the 
  point 
  of 
  view 
  of 
  labour 
  supply. 
  It 
  

   must 
  be 
  admitted 
  that 
  this 
  is 
  a 
  serious 
  drawback, 
  and 
  it 
  is 
  questionable 
  if 
  such 
  

   selection 
  could 
  be 
  practised 
  on 
  estates 
  in 
  the 
  Colony 
  at 
  the 
  present 
  time. 
  

  

  Bearing 
  this 
  in 
  mind, 
  it 
  appeared 
  that 
  some 
  method 
  of 
  treatment 
  for 
  seed-cane 
  

   would 
  be 
  necessary. 
  Such 
  experiments 
  have 
  been 
  carried 
  out 
  by 
  Holloway 
  and 
  

   Loftin, 
  as 
  well 
  as 
  others, 
  but 
  they 
  did 
  not 
  prove 
  effective 
  in 
  the 
  destruction 
  of 
  moth- 
  

   borer 
  larvae. 
  The 
  treatment, 
  however, 
  in 
  no 
  instance 
  extended 
  for 
  more 
  than 
  one 
  

   hour. 
  

  

  Local 
  conditions 
  suggested 
  the 
  immersion 
  of 
  tops 
  in 
  water, 
  for 
  with 
  a 
  very 
  complete 
  

   system 
  of 
  canals 
  as 
  exists 
  on 
  estates 
  in 
  this 
  Colony, 
  and 
  punts 
  for 
  transportation, 
  

   it 
  would 
  be 
  both 
  practical 
  and 
  cheap. 
  With 
  this 
  object 
  in 
  view 
  experiments 
  were 
  

   carried 
  out 
  on 
  the 
  immersion 
  of 
  tops 
  in 
  vessels 
  containing 
  water 
  for 
  periods 
  varying 
  

   from 
  24 
  to 
  72 
  hours. 
  The 
  results 
  of 
  these 
  experiments 
  are 
  given 
  in 
  Table 
  III. 
  

  

  TABLE 
  III. 
  

  

  Effect 
  on 
  Moth-borer 
  Larvae 
  of 
  Immersion 
  of 
  Tops. 
  

  

  Time 
  

  

  No. 
  of 
  

  

  Number 
  of 
  

  

  Number 
  of 
  

  

  Percentage 
  

  

  Total 
  

  

  soaked, 
  

  

  tops 
  

  

  borers 
  found. 
  

  

  borers 
  killed. 
  

  

  mortality. 
  

  

  mortality, 
  

  

  hours. 
  

  

  soaked. 
  

  

  

  

  

  

  

  

  per 
  cent. 
  

  

  Larvae. 
  

  

  Pupae. 
  

  

  Larvae. 
  

  

  Pupae. 
  

  

  Larvae. 
  

  

  Pupae. 
  

  

  24 
  

  

  100 
  

  

  10 
  

  

  2 
  

  

  9 
  

  

  2 
  

  

  90-0 
  

  

  100-0 
  

  

  91-6 
  

  

  24 
  

  

  100 
  

  

  6 
  

  

  

  

  4 
  

  

  

  

  66-6 
  

  

  

  66-6 
  

  

  40 
  

  

  100 
  

  

  11 
  

  

  5 
  

  

  10 
  

  

  5 
  

  

  90-7 
  

  

  100-0 
  

  

  93-7 
  

  

  45 
  

  

  100 
  

  

  25 
  

  

  9 
  

  

  24 
  

  

  8 
  

  

  96-0 
  

  

  88-8 
  

  

  94-1 
  

  

  48 
  

  

  53 
  

  

  12 
  

  

  3 
  

  

  11 
  

  

  3 
  

  

  91-6 
  

  

  100-0 
  

  

  93-3 
  

  

  48 
  

  

  375 
  

  

  103 
  

  

  43 
  

  

  85 
  

  

  43 
  

  

  82-5 
  

  

  100-0 
  

  

  87-6 
  

  

  48 
  

  

  100 
  

  

  11 
  

  

  3 
  

  

  10 
  

  

  3 
  

  

  90-9 
  

  

  100-0 
  

  

  92-8 
  

  

  48 
  

  

  100 
  

  

  5 
  

  

  

  

  5 
  

  

  

  

  100-0 
  

  

  

  100-0 
  

  

  62 
  

  

  203 
  

  

  21 
  

  

  8 
  

  

  18 
  

  

  8 
  

  

  85-7 
  

  

  100- 
  

  

  89-6 
  

  

  72 
  

  

  200 
  

  

  13 
  

  

  7 
  

  

  12 
  

  

  7 
  

  

  92-3 
  

  

  100-0 
  

  

  95-0 
  

  

  72 
  

  

  214 
  

  

  16 
  

  

  2 
  

  

  16 
  

  

  2 
  

  

  100-0 
  

  

  100-0 
  

  

  100-0 
  

  

  72 
  

  

  365 
  

  

  12 
  

  

  4 
  

  

  12 
  

  

  4 
  

  

  100-0 
  

  

  100-0 
  

  

  100-0 
  

  

  84 
  

  

  377 
  

  

  23 
  

  

  7 
  

  

  22 
  

  

  7 
  

  

  95-6 
  

  

  100-0 
  

  

  96-6 
  

  

  It 
  will 
  be 
  seen 
  from 
  the 
  above 
  that 
  72 
  hours' 
  immersion 
  in 
  water 
  kills 
  all 
  the 
  moth- 
  

   borer 
  larvae 
  and 
  pupae 
  contained 
  in 
  the 
  tops. 
  

  

  See 
  page 
  465. 
  

  

  